21537398 has 8 divisors (see below), whose sum is σ = 32915808. Its totient is φ = 10565464.

The previous prime is 21537391. The next prime is 21537427. The reversal of 21537398 is 89373512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×21537398² = 927719025220808, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21537391) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 101486 + ... + 101697.

It is an arithmetic number, because the mean of its divisors is an integer number (4114476).

Almost surely, 2^21537398 is an apocalyptic number.

21537398 is a deficient number, since it is larger than the sum of its proper divisors (11378410).

21537398 is a wasteful number, since it uses less digits than its factorization.

21537398 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 203238.

The product of its digits is 45360, while the sum is 38.

The square root of 21537398 is about 4640.8402256488. The cubic root of 21537398 is about 278.2260208375.

The spelling of 21537398 in words is "twenty-one million, five hundred thirty-seven thousand, three hundred ninety-eight".