21347940 has 24 divisors (see below), whose sum is σ = 59774400. Its totient is φ = 5692768.

The previous prime is 21347929. The next prime is 21347951. The reversal of 21347940 is 4974312.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21347929) and next prime (21347951).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 21347898 and 21347907.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 177840 + ... + 177959.

It is an arithmetic number, because the mean of its divisors is an integer number (2490600).

Almost surely, 2^21347940 is an apocalyptic number.

21347940 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21347940 is an abundant number, since it is smaller than the sum of its proper divisors (38426460).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21347940 is a wasteful number, since it uses less digits than its factorization.

21347940 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 355811 (or 355809 counting only the distinct ones).

The product of its (nonzero) digits is 6048, while the sum is 30.

The square root of 21347940 is about 4620.3831009993. The cubic root of 21347940 is about 277.4077934056.

The spelling of 21347940 in words is "twenty-one million, three hundred forty-seven thousand, nine hundred forty".