21491948 has 6 divisors (see below), whose sum is σ = 37610916. Its totient is φ = 10745972.

The previous prime is 21491941. The next prime is 21491957. The reversal of 21491948 is 84919412.

It is not an unprimeable number, because it can be changed into a prime (21491941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2686490 + ... + 2686497.

It is an arithmetic number, because the mean of its divisors is an integer number (6268486).

Almost surely, 2^21491948 is an apocalyptic number.

It is an amenable number.

21491948 is a deficient number, since it is larger than the sum of its proper divisors (16118968).

21491948 is a wasteful number, since it uses less digits than its factorization.

21491948 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5372991 (or 5372989 counting only the distinct ones).

The product of its digits is 20736, while the sum is 38.

The square root of 21491948 is about 4635.9408969485. The cubic root of 21491948 is about 278.0301711470.

The spelling of 21491948 in words is "twenty-one million, four hundred ninety-one thousand, nine hundred forty-eight".