21148957 has 4 divisors (see below), whose sum is σ = 22262080. Its totient is φ = 20035836.

The previous prime is 21148927. The next prime is 21148973. The reversal of 21148957 is 75984112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21148957 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21148927) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 556533 + ... + 556570.

It is an arithmetic number, because the mean of its divisors is an integer number (5565520).

Almost surely, 2^21148957 is an apocalyptic number.

It is an amenable number.

21148957 is a deficient number, since it is larger than the sum of its proper divisors (1113123).

21148957 is a wasteful number, since it uses less digits than its factorization.

21148957 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1113122.

The product of its digits is 20160, while the sum is 37.

The square root of 21148957 is about 4598.7995172653. The cubic root of 21148957 is about 276.5432005024.

The spelling of 21148957 in words is "twenty-one million, one hundred forty-eight thousand, nine hundred fifty-seven".