21357967 has 12 divisors (see below), whose sum is σ = 22855536. Its totient is φ = 19953920.

The previous prime is 21357943. The next prime is 21357979. The reversal of 21357967 is 76975312.

It is not a de Polignac number, because 21357967 - 2¹⁹ = 20833679 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 (21357937) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 75867 + ... + 76147.

It is an arithmetic number, because the mean of its divisors is an integer number (1904628).

Almost surely, 2^21357967 is an apocalyptic number.

21357967 is a deficient number, since it is larger than the sum of its proper divisors (1497569).

21357967 is a wasteful number, since it uses less digits than its factorization.

21357967 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 578 (or 561 counting only the distinct ones).

The product of its digits is 79380, while the sum is 40.

The square root of 21357967 is about 4621.4680567975. The cubic root of 21357967 is about 277.4512188690.

The spelling of 21357967 in words is "twenty-one million, three hundred fifty-seven thousand, nine hundred sixty-seven".