21967491 has 32 divisors (see below), whose sum is σ = 36617728. Its totient is φ = 11404800.

The previous prime is 21967489. The next prime is 21967511. The reversal of 21967491 is 19476912.

It is not a de Polignac number, because 21967491 - 2¹ = 21967489 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a plaindrome in base 11.

It is not an unprimeable number, because it can be changed into a prime (21967441) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 17691 + ... + 18891.

It is an arithmetic number, because the mean of its divisors is an integer number (1144304).

Almost surely, 2^21967491 is an apocalyptic number.

21967491 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21967491 is a deficient number, since it is larger than the sum of its proper divisors (14650237).

21967491 is a wasteful number, since it uses less digits than its factorization.

21967491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1291.

The product of its digits is 27216, while the sum is 39.

The square root of 21967491 is about 4686.9490076168. The cubic root of 21967491 is about 280.0658476086.

The spelling of 21967491 in words is "twenty-one million, nine hundred sixty-seven thousand, four hundred ninety-one".