21537091 has 2 divisors, whose sum is σ = 21537092. Its totient is φ = 21537090.

The previous prime is 21537073. The next prime is 21537107. The reversal of 21537091 is 19073512.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21537091 is a prime.

It is a super-3 number, since 3×21537091³ (a number of 23 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (21537001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10768545 + 10768546.

It is an arithmetic number, because the mean of its divisors is an integer number (10768546).

Almost surely, 2^21537091 is an apocalyptic number.

21537091 is a deficient number, since it is larger than the sum of its proper divisors (1).

21537091 is an equidigital number, since it uses as much as digits as its factorization.

21537091 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1890, while the sum is 28.

The square root of 21537091 is about 4640.8071496239. The cubic root of 21537091 is about 278.2246988611.

The spelling of 21537091 in words is "twenty-one million, five hundred thirty-seven thousand, ninety-one".